Package ptolemy.plot

Class PlotLive

  • All Implemented Interfaces:
    java.awt.image.ImageObserver, java.awt.MenuContainer, java.awt.print.Printable, java.io.Serializable, java.lang.Runnable, javax.accessibility.Accessible, PlotBoxInterface, PlotInterface
    Direct Known Subclasses:
    PlotLiveDemo
    public abstract class PlotLive
extends Plot
implements java.lang.Runnable
    Plot signals dynamically, where points can be added at any time and the display will be updated. This should be normally used with some finite persistence so that old points are erased as new points are added. Unfortunately, the most efficient way to erase old points is to draw graphics using the "exclusive or" mode, which introduces quite a number of artifacts. When lines are drawn between points, where they overlap the points the line becomes white. Moreover, if two lines or points overlap completely, they disappear.

    This class is abstract, so it must be used by creating a derived class. To use it, create a derived class with an addPoints() method. Your class may also set graph parameters like titles and axis labels in the constructor by calling methods in the Plot or PlotBox classes (both of which are base classes). The addPoints() method should call addPoint() of the Plot base class to dynamically add points to the plot. This method is called within a thread separate from the applet thread, so the zooming mechanism and buttons remain live.

    Since:
    Ptolemy II 0.2
    Version:
    $Id$
    Author:
    Edward A. Lee, Christopher Brooks, Contributor: Jeff Lane
    See Also:
    Serialized Form
    Pt.AcceptedRating:
    Yellow (cxh)
    Pt.ProposedRating:
    Yellow (cxh)

    • Constructor Detail

      • PlotLive

        public PlotLive()

    • Method Detail

      • addPoints

        public abstract void addPoints()
        Redefine in derived classes to add points to the plot. Adding many points at once will make the plot somewhat faster because the thread yields between calls to this method. However, the plot will also be somewhat less responsive to user inputs such as zooming, filling, or stopping. In the derived-class implementation, this method should probably be synchronized.

        Jeff Lane points out that if the derived class version of addPoints() does not return quickly, and it seems like then you may want to experiment with addPoints() to not being synchronized.

      • makeButtons

        @Deprecated
public void makeButtons()
        Deprecated.
        Make start and stop buttons. This method is deprecated. Use setButtons() instead.

      • pause

        public void pause()
        Pause the plot. To resume, call start().

      • run

        public void run()
        This is the body of a thread that repeatedly calls addPoints() if the plot is active. To make the plot active, call start(). To pause the plot, call pause(). To stop the plot and destroy the thread, call stop(). The next time start() is called, a new thread will be started. Between calls to addPoints(), this method calls Thread.yield() so that the thread does not hog all the resources. This somewhat slows down execution, so derived classes may wish to plot quite a few points in their addPoints() method, if possible. However, plotting more points at once may also decrease the responsiveness of the user interface.
        Specified by:
        run in interface java.lang.Runnable

      • setButtons

        public void setButtons​(boolean visible)
        If the argument is true, make a start, stop, and fill button visible at the upper right. Otherwise, make the buttons invisible. NOTE: The buttons may infringe on the title space, if the title is long. In an application, it is preferable to provide a menu with the commands. This way, when printing the plot, the printed plot will not have spurious buttons. Thus, this method should be used only by applets, which normally do not have menus.
        Specified by:
        setButtons in interface PlotBoxInterface
        Overrides:
        setButtons in class PlotBox
        Parameters:
        visible - If true, make the fill button appear.
        See Also:
        PlotBox.destroy()

      • start

        public void start()
        Make the plot active. Start a new thread if necessary.

      • stop

        public void stop()
        Stop the plot. The plot thread exits. This should be called by an applet's stop() method.